Cenozoic tetrapod footprints from the Vinchina Basin, La Rioja, Argentina

KRAPOVICKAS, V.; MÁNGANO, M.G; MARSICANO, C.A.

San Rafael, Mendoza

Jornada; XXIV Jornadas Argentinas de Paleontología de Vertebrados; 2009

Museo de San Rafael

Since the Eocene, several thousand meters of sediment have accumulated mostly in non-marine environments in the Vinchina broken-foreland basin at Vinchina, La Rioja. The activity of a wide variety of tetrapods was recorded in different levels of the Vinchina (Oligocene to Early Miocene) and Toro Negro (Miocene to Early Pliocene) formations as indicated by the trace fossil record. Three successive tetrapod associations are recorded in these units. The oldest association of footprints occurs in the Vinchina Formation at Quebrada de La Troya. It consists of avian and mammalian footprints, including tridactyl large cursorial birds, Gruipeda isp., Macrauchenichnus isp., small tridactyl rodent-like mammals and large tetradactyl rodent-like mammals. Specimens recorded by Bonaparte in the 60’s occur near the top of the Vinchina Formation, at Quebrada del Yeso. They were interpreted as produced by several avian and mammalian taxa, such as Rheiformes, Charadriiformes, Ralliformes, Megatheroidea and Macrauchenidae. A new tetrapod ichnofauna was recently documented close to the base of the Lower Member of the Toro Negro Formation at Quebrada de La Troya. It includes avian (Fuscinapeda sirin Vyalov, slender anisodactyl footprint, large incumbent footprint) and mammalian (Macrauchenichnus rector Angulo y Casamiquela, Venatoripesriojanus Frenguelli, small heteropod footprint, kidney-like footprints, and oval impressions) footprints. Tetrapod trace fossil associations of the Vinchina and Toro Negro formations complement our knowledge of NW Argentina ancient faunas based on body fossils, thus adding new valuable documentation of the activity and locomotive behavior of extinct animals.